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United States Department of Agriculture

Agricultural Research Service

Research Project: EFFECTORS OF PATHOGENICITY IN THE STAGONOSPORA NODORUM-WHEAT PATHOSYSTEM, CHARACTERIZATION OF HOW S. NODORUM IS CAUSING DISEASE Project Number: 5442-22000-048-08
Project Type: Reimbursable

Start Date: Feb 01, 2010
End Date: Jan 31, 2014

Objective:
1) The identification of HST-host gene interactions using purified toxins and wheat mapping populations; 2) Identification of proteinaceous toxin genes using purified toxins in conjunction with mass spec analysis to identify candidate genes for further evaluation; 3) Verification of candidate genes using heterologous expression, transformation, and site directed gene disruption; and 4) Mode of actions studies to identify the molecular and biochemical mechanism whereby the toxin is instrumental in causing disease, including protein-protein interaction studies, inhibitor studies, and protein localization studies.

Approach:
Stagonospora nodorum will be used to produce extracts of the proteinaceous host-selective toxins (HSTs) that we have identified. HSTs will be purified and active fractions will be used to identify protein sequences using mass-spectrometry. Each of the presently characterized toxins has been shown to be a protein that interacts with a corresponding host sensitivity gene in an inverse gene-for-gene manner. Candidate genes will be revealed using the S. nodorum genome sequence. Additionally, bioinformatics will be used to scan the S. nodorum genome to identify candidate genes based on signal sequence domains and predicted protein size in addition to other relevant criteria. We have isolated a nonpathogenic strain of S. nodorum that appears to secrete no toxins. We will use this strain to verify toxin gene candidates. Candidate genes will initially be expressed in this isolate to verify toxin production and pathogenicity changes. Lastly, we will continue to identify new toxins using an international S. nodorum collection. This proposal will enhance economic opportunities for agricultural producers. This will be accomplished by providing valuable information to scientists including breeders for the improvement of wheat as a food crop especially as it relates to providing durable resistance sources to growers.

Last Modified: 10/25/2014
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